Damper unit, a damper assembly, methods of making a damper unit and a damper assembly

ABSTRACT

A damper unit for use in a vibration-reducing assembly for a steering wheel is disclosed. An elastomeric damper element is molded on an inner sleeve and includes a plurality of elastomeric ribs forming a radially outer engagement surface, and a plurality of elastomeric support studs, which are mutually spaced in a circumferential direction are flexible in all directions transverse to said axis. Methods for making a damper unit and a damper assembly are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/771,432, filed Jun. 10, 2020, which is the National Phase of PCTInternational Application No. PCT/EP2018/085043, filed on Dec. 14, 2018,which claims priority under 35 U.S.C. § 119(a) to patent applicationSer. No. 17/207,562.4, filed in European Patent Office on Dec. 15, 2017,all of which are hereby expressly incorporated by reference into thepresent application.

TECHNICAL FIELD

The present disclosure generally relates to the field of frequency-tunedvibration dampers for motor vehicles. A damper unit for use in avibration-reducing assembly for a steering wheel is disclosed. Afrequency-tuned vibration damper assembly including one or more suchdamper units is also disclosed, as well as methods of making a damperunit and a frequency-tuned vibration damper assembly.

BACKGROUND

The function of frequency-tuned vibration dampers, also termed tunedmass dampers, dynamic dampers or vibration absorbers, is based on adampened spring-mass system which counteracts and reduces vibrations ina structure or surface to which the damper is connected by using one ormore elastic damper elements for transferring vibrations from avibrating structure to at least one mass which is caused to vibrate outof phase such as to dampen the vibrations. WO 01/92752 A1, WO2013/167524 A1, and WO 2008/127157 A1 disclose examples offrequency-tuned vibration dampers.

In the automotive industry, some steering wheels are provided withfrequency-tuned vibration dampers for reducing steering wheel vibrationscaused by vibrations from the road and engine being transferred to thesteering wheel. In such damper structures, the weight of an airbagmodule may be used as part of the weight of the mass in the spring-masssystem. Also, steering wheels are generally provided with a hornactivation mechanism by which a driver may activate a horn of thevehicle. Horn activation mechanisms of mechanical type typicallycomprise one or more metal spiral springs, referred to as horn springs,for returning the horn activation mechanism to its normal state after ahorn activation. Electronic horn activation mechanisms without hornsprings are also available.

EP 2 085 290 discloses an example of a prior-art vibration-reducingdamper structure for a steering wheel, including an elastic damperelement arranged on a slider which is slidably mounted on a bolt shaft.Vibrations in the steering wheel are transferred by the elastic damperelement to the airbag assembly for dampening purposes. During hornactivation, the slider may slide along the bolt shaft. A conventionalspiral spring is placed on the bolt shaft and is compressed upon hornactivation for bringing the slider back to its normal position when thehorn activation is terminated. One drawback of this prior art is that isthat the assembly of the overall structure is complicated and timeconsuming, increasing manufacturing time and cost.

U.S. Pat. No. 8,985,623 B2 discloses an alternative damper structure fora steering wheel. The overall operation is similar to the one indisclosed in EP 2 085 290 mentioned above, but the elastic element isencapsulated in a rigid multi-part protector structure. The protector isslidably arranged on a shaft and is biased by a horn spring towards thenon-activated position of the horn activation mechanism. This prior-artsolution has essentially the same drawbacks, and actually requiresadditional cost and time of manufacturing the protector.

Other drawbacks in the prior art include difficulties infrequency-tuning, frequency range limitations, in difficulties inmaintaining a frequency tuning, and difficulties in obtaining desiredspring characteristics upon horn activation.

SUMMARY OF INVENTION

In the light of the above, it is an object of the present inventiveconcept to address one or more of the above-mentioned disadvantages ofthe prior art and, to this end, provide (i) a damper unit for use in avibration-reducing damper assembly for a steering wheel, (ii) avibration damper assembly for dampening vibrations in a steering wheel,(iii) a method of manufacturing a damper unit, and (iv) a method ofmaking a frequency-tuned vibration damper assembly.

According to a first aspect, there is provided a damper unit for use ina frequency-tuned vibration damper assembly for a steering wheel, saiddamper unit having an insertion end and an opposite rear end, and beingconfigured to be inserted with its insertion end through a mountingopening provided in a horn plate of said assembly, said damper unitcomprising:

-   -   a sleeve having a central bore extending along an axis, and    -   an elastomeric damper element which molded on a radial outer        side of the sleeve such that the sleeve and the damper element        together form a unitary structure, wherein: the elastomeric        damper element presents an elastomeric insertion part configured        to be inserted into the mounting opening of the horn plate, and        an elastomeric support part configured to define a final        mounting position of the damper unit; the elastomeric insertion        part presents a plurality of elastomeric ribs which extend at        least partially along said axis and are mutually spaced in a        circumferential direction in relation to said axis, said ribs        together forming a radially outer engagement surface configured        to be brought into direct engagement with an inner surface of        said mounting opening; the radially outer engagement surface has        a first radial dimension, and the elastomeric support part has a        second radial dimension, larger than said first radial        dimension; at least some of the elastomeric ribs present a        radially outward extending snap-lock protrusion configured to be        inserted through the mounting opening to snap-lock the damper        unit in its final mounting position; and said elastomeric        support part presents a plurality of elastomeric support studs,        which are mutually spaced in the circumferential direction and        extend at least partially in the direction of said axis, said        elastomeric support studs being flexible in all directions        transverse to said axis.

During the dampening operation, the elastomeric material of the damperelement is compressed in the direction of the vibrations. An advantageobtained by the ribbed configuration is that the elastomeric materialduring the dampening operation may expand out in spaces between theribs. Thereby, the spring constant of the damper element will present amore linear characteristic compared to “compact” prior-art non-ribbeddamper elements having no spaces into which the compressed elastomericmay expand. Using damper units according to the inventive concept thusmakes it possible to configure a dynamic spring-mass system which willstay better tuned to aimed at target frequency or frequencies, resultingin a more efficient and reliable dampening operation.

A further advantage obtained by the ribbed configuration is an increasedflexibility in the frequency tuning during design and manufacturing. Thedampening frequency of the damper assembly may be frequency tuned byvarying the number of ribs, varying the circumferential, radial, and/oraxial dimensions of the ribs and/or varying the spaces between the ribs.Thus, one may use thicker or thinner ribs in the circumferentialdirection; longer or shorter ribs in the axial direction; longer orshorter ribs in the radial direction, etc.

Also, the frequency interval within which the damper element is tunablemay also be expanded and or moved by using a ribbed configurationcompared to prior-art elastomeric damper elements. It may also be easierto design damper units having different damping frequencies in differentdirection by varying the rib design in different directions.

At least some, preferably all, of the elastomeric ribs present aradially outward extending snap-lock protrusion. The snap-lockprotrusions are configured to be inserted into and passed through themounting opening to snap-lock the damper unit in its final mountingposition. During the insertion procedure, the snap-lock protrusions maybe temporarily compressed and/or moved inwards in the radial directionas they pass through the mounting opening. When the damper unit has beeninserted to its final mounting position, the elastomeric snap-lockprotrusions will automatically move and/or expand radially outwards inorder to engage a distal side of the horn plate or a sleeve fixed at themounting opening.

The support part of the elastomeric damper element has a larger radialdimension than the engagement surface of the insertion part. Thedimensions of the support part may be selected sufficiently large toprevent the support part from passing through the mounting openingduring assembly. Thereby, the support part of the elastomeric damperelement may act as an insertion stop during the assembly, defining thefinal mounting position of the damper element relative to the hornplate. In the final assembly, the elastomeric support part willtypically be in direct contact with a rear side of the horn plate or therear side of a sleeve arranged in the mounting opening. In the finalassembly, the support part and the snap-lock protrusions will thus bearranged on opposite sides of the horn plate and together keep thedamper unit in a fixed position in relation to the horn plate.

The support part of the elastomeric damper element presents a pluralityof elastomeric support studs the ends of which are facing the insertionor distal end of the damper unit. The support studs are mutually spacedin the circumferential direction and preferably distributed in 360degrees around the axis. They extend at least partially in the directionof said axis. In preferred embodiments, the extend in parallel with theaxis. The elastomeric support studs are flexible in all directionstransverse to said axis, i.e. including radial directions,circumferential directions and combinations thereof. During assembly,the distal end surfaces of the support studs facing the insertion end ofthe damper unit will be brought into contact with the rear side of thehorn plate in the final mounting position. This contact between thesupport studs and the horn plate will remain during all operations ofthe assembly, both during vibration damping and during horn activation.Due to frictional forces between the support studs and the rear side ofthe horn plate, the support studs will move in the transverse directionin response to the vibration damping operation. A specific advantage ofthis design using individual and transversely flexible support studs onthe rear side of the horn plate is that the vibration damping effect(which occurs substantially on the opposite side of the horn plate only)will be substantially less affected by the interface or contact on therear side between the horn plate and the elastomeric damper element. Iffor instance the steering wheel is vibrating back and forth horizontallyin a clock direction 3 o'clock ↔ 9 o'clock, then support studs locatedat or near positions 3 o'clock and 9 o'clock may flex horizontally,which would be in the radial direction in relation to the center of thesteering wheel, in order not to substantially affect the vibrationdamping function. Support studs located at positions 12 o'clock and 6o'clock may also flex horizontally, which however would be in thecircumferential direction, in order not to substantially affect thevibration damping function. Other support studs would flex in directionsbeing partly radial, partly circumferential.

In some embodiments, especially embodiments in which the damper unit isused in a vibration damper assembly for a steering wheel having amechanical horn activation mechanism relying on an axial movement of thehorn plate, said plurality of support studs form a first set of a firstsupport studs each having a distal end facing axially towards theinsertion end of the damper unit, and said elastomeric support partfurther presents one or more second elastomeric support studs, eachsecond support stud having a distal end facing axially towards theinsertion end of the damper unit and extending at least partially in thedirection of said axis, wherein the distal ends of the first supportstuds are located axially closer to the insertion end of the damper unitthan the distal ends of the second support studs. In preferredembodiments, there are a plurality of such second support studs. In someembodiments, the first and the second support studs may have differentheight.

An advantage obtained by this design is that two desirable but seeminglyincompatible properties may be obtained by one and the same damper unit,one property relating to vibration damping and the other propertyrelating to horn activation. With regard to vibration damping, aflexible interface is preferred between the elastomeric material and therear side of the horn plate as discussed above in order to reduce theinfluence on the vibration damping operation. On the other hand, withregard to horn activation a stiff interface is preferred in order toinitiate the horn spring compression as soon as possible when the driverpresses the horn pad. Since the horn plate is supported by anelastomeric and thus compressible material on its rear side, there is arisk that the horn spring is not compressed until later during the hornactivation since the elastomeric material will first be compressed inthe axial direction upon horn activation before the force may betransferred to the horn spring. This will give an undesired varyingspring constant when the horn pad is pressed, where the horn spring isnot compressed during the initial movement of the horn plate. This“dilemma” may be solved by the design having first and second supportstuds, creating a “dynamic” support interface which changes itsproperties during the movement of the horn plate.

Before horn activation, the first support studs are in contact with therear side of the horn plate, but the second support studs are axiallyspaced form the rear side of the horn plate by an axial gap. The size Aof this axial gap may be in the order of one or few millimeters as anexample. Other sizes are possible. When the driver has just initiatedthe horn activation by pressing a horn activation pad, the horn platewill move, and the first support studs will be compressed. It ispreferred that the first support studs have relatively total limitedcross-sectional dimension or stiffness in order for this compression tooccur. The total “spring constant” of the whole set of the first supportstuds is preferably selected to be less than the spring constant of thehorn spring. Therefore, the compression of the horn spring has not yetstarted. When the first support studs have been axially compressed by anamount A to a degree where their distal end surfaces are flush with thedistal end surfaces of the second set of support studs, the rear side ofthe horn spring will have contact with both the first support studs andnow also the second support studs. The gap A is now eliminated.Accordingly, selecting small dimensions for the first set of supportstuds has the advantage of both ensuring a flexible interface andensuring a fast axial compression during the initial phase of the hornactivation. When the axial gaps A between the second support studs andthe horn plate have been eliminated, the total axial stiffness or totalspring constant of all the first and second support studs in combinationis preferably selected sufficiently large for the horn spring to becompressed when the driver presses the horn activation pad.

In preferred embodiments, if the total axial spring constant of thefirst and the second set of support studs is k1 and k2, respectively,and the spring constant of the horn spring is k3, then the support studsshould preferably be designed such that k1+k2>k3 in in order to ensurethat the horn spring is compressed when the gaps A have been eliminatedand the combined force from the support studs becomes larger than thepre-compression horn spring force given by k3.

In preferred embodiments, k1<k2 or k1<<k2 in order to keep the interfaceas flexible as possible when no horn activation is present. However,other relations between k1 and k2 are also possible. The stiffness orcompressibility of the support studs may be varied in different ways.For instance, the second support studs may have a larger cross-sectiontransverse to the axis of the damper than the first support studs.

In some embodiments, said one or more second support studs form a secondset of a plurality of second support studs which are mutually spaced inthe circumferential direction and which are circumferentially interlacedwith the first supports studs and spaced therefrom. In otherembodiments, there may be only one single second support stud, forexample in the shape of a continuous ring extending circumferentiallyaround the axis of the damper unit

In some embodiments, the horn spring is pre-compressed before hornactivation. In some embodiments, the sleeve of the damper unit is aslider being configured, upon horn activation on the steering wheel, toslide in the direction of said axis along a guide shaft received in saidcentral bore of the slider. In such embodiments, the elastomericvibration damper element may be molded on a first part of the slider,wherein the damper unit may further comprise an elastomeric horn springelement having a horn spring part and an attachment part molded in onepiece with each other. The attachment part of the horn spring elementmay be molded on a second part of the slider. The horn spring part maybe configured to exert a force on the slider in the direction of theaxis before and upon horn activation on the steering wheel.

Embodiments including an elastomeric horn spring integrally formed withthe damper unit present at least the following advantages:

The number of components to manufacture, manage and assemble is reduced.During assembly, the damper unit is already provided with the moldedhorn spring element. Thereby, no separate horn spring has to be handledduring assembly since the horn spring is already in place as an integralcomponent of the damper unit. The mechanical horn spring mechanism isdirectly and automatically obtained upon mounting the slider on theguide shaft.

The horn plate can be quickly and easily connected to the base structureby one or more damper units, wherein each damper unit automaticallyprovides—as a direct result of mounting the unit—both a vibrationdampening function and a horn spring function without any need ofhandling or assembling a separate damping element or a separate hornspring.

It is possible to manufacture a multi-function unitary damper unit bymolding the damper element and the horn spring element in one piece witheach other on the slider in one single molding step. The unitary damperunit—including a slider plus an elastomeric damper element plus a hornspring element—will present a slider function, a vibration dampingfunction and a horn spring function, respectively.

By molding the elastomeric horn spring element on the slider, it ispossible to both manufacture the horn spring and to bond the horn springto the slider in one single molding operation. By molding the hornspring element on the slider, the quality of the final product may beincreased since no separate alignment and mounting of the horn spring isneeded.

The damper unit may also be used with a separate horn spring, such as aconventional metallic spiral spring. In other embodiments, where thedamper units are used in a damper assembly for a steering wheel havingan electronic horn activation instead of a mechanical horn activation,the damper units may be used without any horn springs, just forconnecting the horn plate to the base structure via the elastomericelements in order to achieve the dynamic vibration damping effect.

According to a second aspect, there is provided frequency-tuned damperassembly for dampening vibrations in a steering wheel, said assemblycomprising:

a base structure which is fixed to a steering wheel and presentsvibrations to be dampened;

a horn plate;

one or more damper units according to claim 1, each damper unit beingarranged in an associated mounting opening in the horn plate with itsradially outer engagement surface in direct contact with the horn platefor transferring said vibrations;

one or more guide shafts, each guide shaft being fixed to the basestructure and being received in the central bore of the sleeve of theassociated damper unit; and

a mass which is supported by the base structure via the damper elementsof the damper units for allowing movement of the mass transverse to saidaxis;

wherein the damper element and the mass are configured to operate as afrequency-tuned spring-mass system forming a frequency-tuned dynamicdamper for dampening said vibrations.

In some embodiments of the damper assembly with a mechanical hornactivation, a distal part of the elastomeric damper assembly of eachdamper unit may protrude axially beyond the mounting opening in the hornplace. Upon horn activation, when a driver presses a horn pad of thesteering wheel, the horn plate is moved against the spring force of oneor more horn springs. When the driver subsequently releases the hornpad, the horn plate is moved back to its normal position by the hornsprings. An advantage obtainable by this design is that the elastomericdistal part of the damper element, which protrudes axially beyond themounting opening in the horn plate, may operate as an elastomeric stopelement during the return movement of the horn plate. Upon hornactivation, the distal part of the damper element may move away from thebolt head. When the horn pad is released, the horn springs will push thehorn plate back towards its normal position. During the return movement,the elastomeric distal part of the damper element will engage the bolthead defining a “soft” dampened stop position for the return movement.Thus, the elastomeric damper elements of damper unites used in a damperassembly for a steering wheel may have multiple functions, including butnot limited to transferring radially directed vibrations in thefrequency-tuned dampening operation, and dampening an axially directedhorn mechanism return movement.

As known as such in the prior art, the weight of an airbag assembly inthe steering wheel may be preferably be used as part of the mass for thedynamic damping function of the dynamic spring-mass system in order touse a separate dead weight for this purpose. The weight of the hornplate and of further components supported by the horn plate will alsocontribute to the total weight of the vibrating mass.

In preferred embodiments, the part of the elastomeric damper elementinvolved in the vibration dampening operation is pre-compressed as aresult of the damper unit being inserted and mounted in the horn plate.

As a result of the insertion and mounting of the damper unit, the outerengagement surface of the damper unit is brought into direct engagementwith an inner engagement surface of a mounting opening of the horn platefor transferring the vibrations. The inner engagement surface may beformed by the horn plate as such (made of metal for instance) or by asleeve fixedly connected or molded to the horn plate and extendingaxially from the horn plate for providing an axially extended engagementinterface. Such a sleeve may be a sleeve molded on the horn plate, forinstance by a relatively rigid plastic material.

The vibration-reducing damper assembly comprises at least one, butpreferably a plurality of damper units according to the invention.Optionally the damper units may be configured to dampen vibrations indifferent directions. This may be achieved by using one or more damperunits for one vibration direction, and one or more other damper unitsfor a second vibration direction. It may also be possible to design eachdamper unit such that it may dampen different vibrations in differentdirections.

Preferred embodiments of the damper assembly may comprise one or moredamper units according to any of the dependent claims 2 to 8. Preferredembodiments of the assembly are set out in the dependent claims.

According to a third aspect, there is provided a method of manufacturinga damper unit, comprising:

molding, on a radially outer first part of a sleeve, an elastomericvibration damper element having an elastomeric insertion part configuredto be inserted into a mounting opening of the horn plate, and anelastomeric support part configured to define a final insertion positionof the damper unit; wherein:

-   -   the elastomeric insertion part presents a plurality of        elastomeric ribs which extend at least partially along said axis        and are mutually spaced in a circumferential direction in        relation to said axis, said ribs together forming a radially        outer engagement surface configured to be brought into direct        engagement with an inner surface of a mounting opening;    -   the radially outer engagement surface has a first radial        dimension, and the elastomeric support part has a second radial        dimension, larger than said first radial dimension; and    -   said elastomeric support part presents a plurality of        elastomeric support studs, which are mutually spaced in the        circumferential direction and extend at least partially in the        direction of said axis, said elastomeric support studs being        flexible in all directions transverse to said axis.

According to a fourth aspect of the inventive concept, there is provideda method for use making a frequency-tuned vibration damper assembly fordampening vibrations in a steering wheel, said method comprising:

using one or more damper units, each damper unit comprising a sleevehaving a central bore which extends along an axis, and an elastomericvibration damper element which is molded on a radial outer side of thesleeve such that the sleeve and the damper element together form aunitary structure, said elastomeric vibration damper element having: anelastomeric insertion part presenting one or more radially outwardextending snap-lock protrusions at an insertion end, and a radiallyouter engagement surface axially spaced from the snap-lock protrusions,said radially outer engagement surface having a first radial dimension,and an elastomeric support part which has a second radial dimension,larger than said first radial dimension; and

inserting each damper unit, in an insertion direction, into anassociated mounting opening in a horn plate along an axis of the damperunit, wherein the damper unit is inserted into the mounting openinguntil a final insertion position is reached in which: the radially outerengagement surface of the elastomeric insertion portion is in directcontact with an inner surface of the mounting opening, the snap-lockprotrusions have been inserted through the mounting opening to form asnap-lock of the damper unit in relation to the horn plate, and theelastomeric support part has been brought into axial contact with a rearside of the horn plate.

Specific features of the inventive method of making a frequency-tuneddamper assembly include that the elastomeric damper element and theslider/sleeve are inserted together into the mounting opening of thehorn plate from one side of the horn plate only during the assembly, andthat the elastomeric damper element is inserted in the insertiondirection to such an extent that the elastomeric engagement surface isbrought into engagement with the inner engagement surface of themounting opening, and a distal part of the elastomeric damper elementincluding the snap-lock protrusions projects axially beyond the innerengagement surface of the mounting opening.

A first advantage of the method of making a frequency-tuned damperassembly is that the assembly of the components may be performed in ashorter time since the elastomeric damper element and the slider areinserted into the mounting opening of the horn plate together and fromone side of the horn plate only during the assembly. The elastomericdamper element and the slider form a unitary structure to be assembledfrom said one side of the horn plate.

A second advantage of the method of making a frequency-tuned damperassembly is that the damper unit may easily be snap-locked to themounting plate. The damper unit is inserted to an extent that the one ormore radially outward extending snap-lock protrusions of the elastomericdamper element project over a distal axial edge of the mounting opening.Thereby, the inserted elastomeric damper element may be held in itscorrect position in relation to the horn plate by the snap-lockprotrusions. Since said one or more snap-lock protrusions are integrallyformed with the elastomeric element and, accordingly, are made of anelastomeric material, they may be temporarily radially compressed and/orbent during the insertion step in order to pass through the mountingopening. Thereby, no separate locking element has to be assembled fromthe opposite side of the horn plate, reducing assembly time andmanufacturing costs.

The method of making a damper assembly may include the use of any of theembodiments of damper units as described above or as defined in theclaims. Thus, the damper units may comprise ribs, support studs,integrated elastomeric horn springs. However, other designs are alsopossible, such as designs having no ribs but instead a continuousradially outer engagement surface.

Terminology

In the present disclosure, when an elastomeric element is stated to be“molded” on the sleeve or slider is should be interpreted as therelevant element is first of all a molded detail being manufactured bymolding. Second, the expression “molded” is to be interpreted as therelevant element is created/molded directly on the sleeve or slider, incontrast to prior-art solutions where the relevant element is made as aseparate part, such as in the form of a conventional spiral-shaped metalspring made separately and mounted in the assembly as a separate part.In preferred embodiments, the elastomeric material includes siliconerubber.

In the present disclosure, the term “slider” may refer to an elementwhich is arranged to slide along a guide shaft during horn activation.This is the case when a mechanical horn activation mechanism is used.However, the term “slider” may also refer to a sleeve which is arrangedto be mounted on but not to slide along a guide shaft. This is the casewhen an electronic horn activation is used where the horn plate is notconfigured to move axially relative to the guide shaft during hornactivation.

In the present disclosure, the expression “in contact with the rear sideof the horn plate” is to be interpreted as covering both direct contactwith the horn plate as well as direct contact with a sleeve fixed to thehorn plate around the mounting opening for the damper unit.

In the present disclosure, the terms “bonding” or “bonded” are to beinterpreted as a connection or attachment between the relevant elementand the sleeve or slider preventing the element from falling off from orbeing easily removed from the sleeve or slider. The term “bonding” isthus to be interpreted as an attachment or connection ensuring that therelevant element, as an integral part of the damper unit from anassembly perspective, is being held by the bond in its intended positionon the slider. In embodiments where an element can easily be removedfrom the slider or easily fall of from the slider, such as a cylindricaldamper element having a central bore in which a guide shaft is receivedwithout any mechanical bonding or adhesion acting in the axialdirection, the element is not considered to be “bonded” to the slideralthough radial movement relative to the slider may be restricted.

In the present disclosure, “mechanically bonded” or “mechanical bonding”is to be interpreted as an alternative to “chemical bonding”.Mechanically bonding should be interpreted as a non-chemical attachmentof the relevant element to the slider, ensuring that the relevantelement is mechanically maintained in its intended position on theslider.

In the present disclosure, expressions as “chemically bonded”, “chemicalbonding”, “adhesion” binding or “adhesion” and the like should beinterpreted as an alternative to mechanical bonding. Chemical bonding isconsidered a bonding between molecules. In some embodiments, mechanicaland chemical bonding may be used in combination. A preferred chemicalbonding may be adhesion bonding rather than glue. Chemical bonding maybe provided during molding. In some embodiments, chemical bonding may beobtained by using an overmolding technique with adhesion bonding betweensimilar or related polymers.

In the present disclosure, the term “snap-locking” and the like shouldbe interpreted as a locking mechanism which results in a lockingfunction as a result of the damper unit being inserted into its finalmounting opening. Especially, the term should be interpreted to coveralso embodiments where there is not necessarily a distinct “snap”occurring during the insertion but rather a gradual expansion/movementof the snap-lock protrusion.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept, some non-limiting preferred embodiments, andfurther advantages of the inventive concept will now be described withreference to the drawings in which:

FIG. 1A illustrates a steering wheel of a vehicle.

FIG. 1B illustrates main parts of a vibration-reducing assembly.

FIG. 2 is an exploded view of a vibration-reducing assembly.

FIGS. 3 and 4 are sectional views of the assembly in FIG. 1B.

FIG. 5 is a side view of the assembly in FIG. 1B.

FIGS. 6 and 7 illustrate in larger scale a damper unit mounted in theassembly in FIG. 2 .

FIGS. 8A to 8D illustrate a slider of a 1^(st) embodiment of a damperunit.

FIGS. 9A to 9E illustrate a Pt embodiment of a damper unit.

FIGS. 10A and 10B illustrate a unitary elastomeric body of the damperunit according to the Pt embodiment.

FIGS. 11A and 11B illustrate a 2^(nd) embodiment of a damper unit.

FIGS. 12A and 12B illustrate a 3^(rd) embodiment of a damper unit.

FIGS. 13A to 13D illustrate a slider of a 4^(th) embodiment of a damperunit.

FIGS. 14A to 14C illustrate a unitary elastomeric body of the damperunit according to the 4^(th) embodiment.

FIGS. 15A to 15C illustrate the damper unit according to the 4thembodiment.

FIGS. 16A to 16F illustrate an assembly method using the damper unitaccording to the 4^(th) embodiment.

FIGS. 17A to 17C illustrate a horn activation of an assembly includingdamper units according to the 4th embodiment.

FIGS. 18A to 18C illustrate a unitary elastomeric body of a damper unitaccording to a 5th embodiment.

FIGS. 19A to 19C illustrate a damper unit according to the 5thembodiment.

FIGS. 20A to 20F illustrate an assembly method using the damper unitaccording to the 5th embodiment.

FIG. 21 illustrates an alternative assembly method using the damper unitaccording to the 5th embodiment.

FIG. 22 is a cross section of the 5th embodiment.

FIG. 23A to 23C illustrate a horn activation of an assembly includingdamper units according to the 5th embodiment.

FIG. 24A to 24C show a damper unit according to a further inventiveconcept.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present inventive concept relates in general to the field offrequency-tuned vibration dampers, also referred to as dynamic dampers.Such dampers may be used to dampen vibrations in a vibrating surface orstructure, such as a vibrating component like a steering wheel of amotor vehicle. A dynamic vibration damper comprises a mass acting as avibration body, and at least one elastic damper element. The mass andthe least one elastic damper element together provide a dampenedspring-mass system, and may be connected to the vibrating structure,optionally by means of an intermediary component.

The weight of the mass, and the stiffness and damping of the elasticdamping element are selected to provide a damping effect on thevibrating structure, which can be expected to vibrate at one or morepredetermined target frequencies. When the vibrating structure vibratesat a target frequency, the mass is caused to oscillate/resonate at thesame frequency as the structure but out of phase, such that thevibration of the structure is substantially dampened. The mass mayvibrate with an amplitude substantially greater than the vibrationamplitude of the vibrating structure.

The present inventive concept relates to a damper unit for use in such adynamic damper assembly arranged in a steering wheel of a vehicle fordampening steering wheel vibrations.

1^(st) Embodiment

FIG. 1A illustrates a steering wheel 2 in a motor vehicle 4. Vibrationsfrom the road and the engine may be transferred to the steering wheel 2.These steering wheel vibrations may be perpendicular to the steeringcolumn, as indicated by up-down and left-right arrows. The steeringwheel 2 is provided with a vibration-reducing assembly 6, which isschematically indicated by a dashed box inside the steering wheel 2 andwhich is configured to dynamically dampen at least some of the steeringwheel vibrations.

As known in the art, the steering wheel 2 is also provided with a hornactivation mechanism for activating a horn (not shown) of the vehicle 4.To this end, a horn activation pad 8 is arranged in the center of thesteering wheel 2 to be pressed by the driver upon horn activation. Whenthe driver releases the horn activation pad 8, the horn activationmechanism returns to its non-activated or initial state by means of oneor more horn springs. In the illustrated embodiment, the horn activationmechanism is of mechanical type. There exist horn activation mechanismsof electronic design also, not including horn springs.

Furthermore, an airbag assembly may be arranged inside the steeringwheel 2 under the horn activation pad 8. FIG. 1B schematically shows apart 10 of a gas generator of an airbag assembly. In the presentembodiment, the weight of the airbag assembly is used as at least partof the total weight of the mass used in the vibration-reducingspring-mass system. Thereby, the use of separate deadweights for thispurpose may be avoided or substantially reduced.

The vibration-reducing assembly 6 inside the steering wheel 2 isarranged on and supported by a base structure or armature 12 fixed tothe steering wheel 2. The vibrations in the steering wheel 2 are thuspresent in the base structure 12 also, as indicated by vibrations V inFIG. 7 perpendicular to the steering column. The vibration-reducingassembly 6 comprises a horn plate 14 on which the airbag assembly ismounted, including the gas generator and the airbag. In a preferredembodiment, the horn plate 14 is made of metal and is optionallyprovided with a plastic cover made of a relatively rigid plasticmaterial molded on the horn plate 14, including a top cover 16 and abottom cover 18. The horn plate 14 is provided with three openings, eacharranged to receive part of a damper unit 40 as will be described below.In the illustrated embodiment, a cylindrical sleeve 20 is arrangedaround each opening in the horn plate 14 and extends above the plane ofthe horn plate 14. The sleeves 20 may by molded in one piece with theplastic cover 16, 18, thus being rigidly connected to the horn plate 14.In other embodiments, the sleeves 20 may be dispensed with.

As shown in FIG. 2 , the base structure 12 may comprise three supports13, projecting towards the horn plate 14 and each provided with athreaded bolt hole. A separate bracket 22 is supported on the supports13. The bracket 22 has a through opening or mounting opening 24 alignedwith each support 13. Adjacent each mounting opening 24, the bracket 22presents a horn spring support surface 26 facing the horn plate 14, andon the opposite side a bracket support surface 28 facing the basesupport 12. In the assembled state (FIG. 7 ), the bracket 22 issupported at the bracket support surfaces 28 by the supports 13.

The bracket 22 is a multi-function bracket for supporting variouscomponents, and may especially comprise parts of the horn switchmechanism of the steering wheel 2, here in the form of four contactstuds 30 which project towards the horn plate 14 and are aligned withcorresponding contact pads 15 protruding from the bottom side of thehorn plate 14. As shown in FIG. 5 , the contact studs 30 and the contactpads 15 are normally located at a distance D from each other. Upon hornactivation, the horn plate 14 is pressed towards the bracket 22 untilthe contact pads 15 and the contact studs 30 are brought into electricalengagement for activating the horn, and at the same time a movement stopfor the horn plate 14. As an illustrative example, the distance D may bein the order of a few millimeters.

The horn plate 14 with the airbag assembly fixed thereto is movablysupported on the base structure 12 via three damper units 40. It may benoted that although this unit is termed “damper unit” in thisdisclosure, a damper unit 40 provides both a vibration damping functionand a separate horn spring function as will be described below. Eachdamper unit 14 is configured to allow the mass represented at least bythe horn plate 14 and the airbag assembly to move (i) perpendicular tothe axis A of the damper unit 40 for vibration damping purposes, and(ii) along the main axis A for horn activation purposes. A 1^(st)embodiment of a damper unit 40 will now be described with reference toFIGS. 8A to 8D, FIGS. 9A to 9D, and FIGS. 10A and 10B.

The damper unit 40 comprises a slider 50, a damper element 70 and a hornspring element 90. In a preferred embodiment, the slider 50, the damperelement 70 and the spring element 90 may be bonded together into oneunit 40, such that these three components form a unitary structure readyto be connected to the base structure 12 and the horn plate 14. Thecomponents 50, 70 and 90 may be mechanically and/or chemically bondedtogether, in the sense that they cannot easily be taken apart from eachother.

FIGS. 8A to 8D illustrate a 1^(st) embodiment of the slider 50. Theslider 50 may be made from a relatively rigid material, such as asuitable synthetic resin material. In horn activation structures of themechanical type, the slider is arranged to slide on a guide shaft uponhorn activation as will be described below. The slider 50 comprises atubular element 52 defining a through bore 54 for receiving the guideshaft, and a radially extending flange 56. The flange 56 divides thetubular element 52 into a first tubular part 58 on one side of theflange 56, and a second tubular part 60 on the axially opposite side ofthe flange 56. In the illustrated embodiment, the first tubular part 58is longer than the second tubular part 60. The flange 56 presents one ormore locking openings here in the form of a plurality of axiallyoriented through holes 62 used for mechanically bonding the damperelement 40 and the horn spring element 90 together and to the slider 50.The flange 56 also serves to take up spring forces from the horn springelement 90, and to transfer axial forces between the slider 50 and thedamper element 70.

Reference is now made to FIG. 9A to 9E illustrating a 1^(st) embodimentcomplete damper unit 40. The elastic damper element 70 is arranged onthe first slider part 58. The elastic damper element 70 is made of anelastomeric material, such as silicone rubber, suitable for use as theelastic spring element in a dynamic damper. The damper element 70 isconfigured to operate together with the mass represented by at least theairbag module and the horn plate 14 as a spring-mass system forming afrequency-tuned dynamic vibration damper for dampening the vibrations Vin the base structure 12 and the steering wheel 2.

In the illustrated embodiment, the damper element 70 has a generalcylindrical shape with a distal end 71 facing away from the flange 56, aproximal end 72 facing towards the flange 56, and an outer engagementsurface 75. As an illustrative, but non-limiting example the axiallength of the damper element can be in the order of 7 mm. In the finalvibration-reducing assembly as shown in FIG. 7 , the outer engagementsurface 75 of each damper element 70 is in engagement with an innerengagement surface 21 of an associated sleeve 20 on the horn plate 14for transferring vibrations to the horn plate 14. In the illustratedembodiment, the axial length of the damper element 70 correspondsessentially to the axial length of the first slider part 58 but extendsaxially a short distance beyond the distal end of the first slider part58. The proximal end 72 of the damper element 70 is in contact with theflange 56. The distal end 71 of the damper element 70 has an increasedouter diameter for forming a radially outward extending ring-shapedsnap-lock protrusion 73. The proximal end 72 of the damper element 70has an even larger diameter and is arranged to extend under the hornplate 14 in the assembly 6. The proximal end 72 may present an upwardlydirected support ring 74 defined by a ring-shaped groove 76 for reasonsthat will be explained below.

In the illustrated 1^(st) embodiment, the damper element 70 is dividedinto a plurality of axially extending ribs 77 (FIG. 9D), which arecircumferentially distributed about the axis A of the damper unit 40 andwhich define spaces 78 there between. The radially outer surfaces of theribs 77 together form the outer engagement surface 75 of the damperelement 70. The operation and advantages obtained by the ribs 77 and thespaces 78 will be explained below. In other embodiments, the damperelement 40 may have the form of a circumferentially unbroken cylinderdefining a continuous outer engagement surface.

The horn spring element 90 of the damper unit 40 is arranged on a secondpart of the slider 50, in this embodiment on the axially opposite sideof the flange 56 on the second tubular part 60 and also on part of theflange 56. The horn spring element 90 is made from an elastomericmaterial and comprises a horn spring part 94 and an attachment part 92(FIG. 9C), which are molded from an elastomeric material in one piecewith each other. During molding of the horn spring element 90, at leastthe attachment part 92 thereof is molded on the slider 50 such that thehorn spring element 90 is correctly positioned on the slider 50 whenbeing manufactured.

As best shown in FIG. 9C, the attachment part 92 of the horn springelement 90 has an L-shaped cross section with one leg in contact withthe shorter tubular part 60 of the slider 50 and one leg in contact withthe flange 56. In other embodiments, the shorter tubular part 60 isdispensed with and the attachment part 92 may engage the flange 56 only.

The elastomeric material used for the horn spring element 90 may be anyelastomeric material suitable to provide the aimed-at horn springfunction, depending on the required spring constant. In a preferredembodiment, the material comprises silicone rubber. The same elastomericmaterial may be used for molding the damper element 40 and the hornspring element 90, especially if these elements are molded in one piecewith each other. In the illustrated first embodiment, the horn springpart 94 is bellow-shaped in order to provide the spring action in thedirection of the axis A. Other embodiments may have a different springdesign, relying in part or only on compression rather than flexing as inthe bellow-shaped design. The spring constant may be varied by varyingone or more parameters of the horn spring part 94, such as the material,the axial length, the diameter, the wall thickness, and thebellow-design (angles, etc.). It may also be possible to use a “broken”design presenting openings and/or separate spring legs, which also wouldpresent further tuning options for the spring characteristics.

In the final vibration-reducing assembly 6, the molded horn spring part94 is configured to act as a horn spring in the direction of the axis A,to exert a spring force on the horn plate 14 via the slider 50 and thedamper element 40. The spring force will be present for returning thehorn plate 14 when the horn activation is terminated. Due to thepre-compression of the horn spring part 94, the spring force is presentas a biasing spring force in the non-activated state also. An advantageobtained thereby, is that the spring force generated by the horn springmay be available earlier as the driver operates the horn.

In the illustrated first embodiment, the horn spring element 90 ismolded directly on the slider 50, avoiding the need to manufacture ametal spiral spring separately, and to attach and/or align such aseparate metal spiral spring in relation to the slider during theassembly. At present, overmolding is considered a preferred moldingmethod, but other techniques may also be considered, such as 2Kinjection molding where both the slider 50 and the elastomericcomponents are manufactured using one single 2K injection moldingmachine. Although not presently preferred, different molding techniquesmay be used for the damper element 70 and the horn spring element 90. Inpreferred embodiments, the horn spring element 90 is not only molded onthe slider 50 but is also bonded to the slider 50. The bonding may bemechanical (including frictional bonding) and/or chemical.

In the illustrated 1^(st) embodiment, the horn spring element 90 ismechanically bonded to the slider 50 in order to keep the horn springelement 90 in the illustrated position on the slider 50. This isachieved by a plurality of elastomeric locking elements 100, which aremolded in one piece with the horn spring element 90 and which are inlocking engagement with the locking openings 62 in the flange 56. In theillustrated embodiment, the damper element 40 also is mechanicallybonded to the slider 50 to keep the damper element 40 in the illustratedposition on the slider 50. This is also achieved by the locking elements100. In the preferred embodiment, the same locking elements 100 are usedfor bonding both the horn spring element 90 and the damper element 40,such that the elastomeric horn spring element 90, the elastomeric damperelement 40 and the locking elements 100 are molded together as oneunitary body, mechanically bonded to the slider 50 by the throughopenings 62. For explanatory purposes only, this unitary elastomericbody 70, 90, 100 is shown without the slider 50 in FIGS. 10A and 10B. Inthis embodiment, there may also be a frictional bonding between theelastomeric elements 70, 90 and the tubular parts of the slider 50.

In some embodiments, one or both of the damper element 40 and the hornspring element 90 may be chemically bonded to the slider 50 by adhesion.It is also possible to use both mechanical bonding as disclosed in thedrawings, and chemical adhesion, for one or both of the damper element40 and the horn spring element 90. The chemical adhesion may beimplemented during molding. It is also possible to rely on frictionalbonding, only or in part. Frictional bonding may be obtained by apost-molding shrinking of the elastomeric material.

A method for assembling the vibration-reducing assembly 6 using a numberof damper units 40 according to the 1^(st) embodiment will now bedescribed with reference to FIGS. 2 to 7 . The sequence or order ofsteps as described here may be varied. As a first step, the bracket 22may be placed upon the supports 13 of the base structure 12. As a secondstep, each damper unit 40, including the slider 50 and the ribbed-shapeddamper element 70 forming a unitary structure, may be inserted frombelow in FIG. 2 into an associated mounting opening 24 of the horn plate14.

It should be noted that slider 50 and the elastomeric damper element 70of each damper unit 40 are inserted together as a unit and from one sideonly of the horn plate 14. During insertion of the damper element 70,the radially outer engagement surface 75 of the damper element 70 isbrought into engagement with the inner engagement surface 21 of thecorresponding sleeve 20, such that steering wheel vibrations V may betransferred from the damper element 70 to the horn plate 14. Preferably,the radial dimensions are selected such that the damper element 70 issomewhat radially compressed between the slider 50 and the innerengagement surface 21 of the sleeve 20.

During the insertion of the damper element 70, the support ring 74integrally formed with the damper element 70 will engage the bottom sideof the horn plate 14 as shown in FIG. 7 , defining the final insertionposition. During the insertion of the damper element 70, the uppersnap-lock protrusion 73 of the damper element 70 will be temporarilycompressed in order to pass the sleeve 20. In the final position, thesnap-lock protrusion 73 will extend over the upper edge of the sleeve20. Thereby, the support ring 74 and the snap-lock protrusion 73 willtogether ensure that the damper element 70 is held correctly axiallypositioned/locked in relation to the horn plate 14. No separate lockingelements are needed, and the axial locking is automatically obtainedduring the one-sided insertion of the damper unit. It will also be notedthat an axial distal part of the elastomeric damper element 70 in this1^(st) embodiment will extend axially beyond the distal edge of thesleeve 20.

When the damper elements 70 have been correctly positioned in the hornplate 14, a bolt 120 may be inserted into the bore 54 of each slider 50.Each bolt 120 has a bolt head 126, a cylindrical guide shaft 122 and athreaded end 124. The tubular part 52 of the slider 50 may slide alongthe guide shaft 122. As shown in FIG. 7 , the bolts 120 are secured inthe bolt holes of the supports 13 of the base structure 12. During thefinal fastening of each bolt 120, a pre-compression of the correspondinghorn spring part 94 is obtained. As a non-limiting example, a hornspring part may be pre-compressed from 10 mm to 7 mm during assembly andthen further compressed one or a few mm upon horn activation. In thefinal assembly, the distal end 95 of each horn spring part 94 engagesthe associated horn spring support surface 26 of the bracket 22. In thefinal assembled state, the bolt head 126 is in axially engagement withthe upper end 71 of the elastomeric damper element 70, with thesnap-lock protrusion 73 projecting between the sleeve 20 and the bolthead 126.

It will be understood that the disclosed method of making the damperunit 40 and assembling a vibration-reducing assembly using the inventivedamper units 40 may provide substantial advantages in terms ofmanufacturing cost and time, but also in terms of quality. Compared withthe prior art where a number of individual parts have to bemanufactured, handled and assembled, the inventive concept makes itpossible to establish—at each damper unit 40— both the damper functionand the horn spring function using one unitary damper unit 40 only,together with a simple bolt 120, compared to the prior art where anumber of different components must be handled and assembled, often fromdifferent sides of the horn plate 14.

The operation of the horn activation mechanism of the assembly 6 is asfollows: When the horn mechanism is not activated by the driver, eachpre-compressed or biased horn spring part 94 presses against the flange56 of the slider 50, urging the slider 50 upwards in a direction awayfrom the base structure 12. The axial spring force is transferred viathe flange 56 to the damper element 70, and via the support ring 74 tothe horn plate 14. It will here be noted that the bolt 120 has multiplefunctions:

-   -   the bolt 120 provides the guide shaft 122 for the axial movement        of the slider 50 during horn activation;    -   the bolt head 126 defines an upper axial stop for the axial        movement of the damper unit 40, and    -   the bolt head 126 assists in locking the damper unit 40 in place        in relation to the horn plate 14 by pressing on the top of the        damper element 70.

In the illustrated embodiment, the distal end 71 of the damper element70 extends a short distance beyond the upper edge of the sleeve 20,whereby the upper stop position of the damper unit 40 is defined by asoft engagement between the end 71 of the damper element 70 and the bolthead 120.

Upon horn activation, when the driver presses the horn pad 8 on thesteering wheel 2, the horn plate 14 is pressed towards the basestructure 12. The force is transferred via the damper element 40 to theslider 50, which is thereby displaced along the guide shaft 122compressing the horn spring part 94 further in the axial direction untilthe distance D in FIG. 5 is reduced to zero and the horn switch 15, 30is closed. When the pressure on the horn pad 8 is released, the hornspring part 94 will return the horn plate 14 to its normal position,whereby the soft engagement between the elastomeric end portion 71 andthe bolt head 124 provides a “soft” stop.

The vibration damping function of the assembly 6 is as follows: Steeringwheel vibrations V (FIG. 7 ) occurring in the steering wheel 2 and thebase structure 12 are transferred via the bolts 120 and the sliders 50to the elastomeric damper elements 70. The elastomeric damper elements70 transfer the steering wheel vibrations V to the horn plate 14 via thesleeves 20, thereby causing the mass (represented by the weight of thehorn plate, the airbag assembly and any other details supported by thehorn plate 14) to vibrate out of phase such that the vibrations V in thesteering wheel 2 are dynamically dampened. During the vibrationdampening, the radial compression of the elastomeric material of thedamper elements 70 will vary. Thanks to the ribbed design of the damperelements 70, the elastomeric material may expand into the spaces 78between the ribs 77 during vibration. This design gives an advantageousmore linear relation between the damper compression and the springconstant of the damper element 70. In a non-ribbed, solid cylinder ofelastomeric material, the material has no such “escape”, resulting in amore non-linear spring constant, making the dynamic dampening functionless efficient because matching the target frequency will be moredifficult. A further advantage obtained by the ribbed configuration isan increased flexibility in the frequency tuning during design andmanufacturing. The dampening frequency of the assembly may be tuned byvarying one or more parameters such as the number of ribs 77, thecircumferential, radial, and/or axial dimensions of the ribs 77 and thespaces 78 between the ribs 77. Thus, one may use thicker or thinnerribs, longer or shorter ribs in the axial direction, longer or shorterribs in the radial direction, etc. Also, the frequency interval withinwhich the damper element 70 is tunable may be shifted and/or expanded byusing a ribbed configuration compared to prior-art damper elements.

During the vibration damping operation, the horn plate 14 will thus becaused to move in directions perpendicular to the axis A, especially inrelation to the lower or proximal part 72 of the damper element 70supporting the horn plate 14 in the axial direction. Since the radiallymoving horn plate 14 at its rear side is in direct contact with thesurface of the lower part 72, such radial movements of the horn plate 14may give rise to unwanted frictional movements and silicone wear at theinterface between the bottom side of the horn plate 14 and the damperelement 70 at reference numeral 74 in FIG. 7 . Also, this direct axialcontact between the lower part 72 of the damper element 70 and the rearside of the horn plate 14 may influence the damping function (tuning) ina negative way. This is the reason for providing the ring shaped groove76. Thereby, the support ring 74 will be more free to move in theleft-right direction in FIG. 7 , together with a left-right movement ofthe horn plate 14 during damping, resulting in less frictional movementsbetween the horn plate 14 and the damper element 70, and also resultingin a “de-coupling” of the vibration dampening from the contact betweendamper element part 70 and the rear side of the horn plate 14.

2^(nd) Embodiment

FIGS. 11A and 11B illustrate a 2^(nd) embodiment of a damper unit 240.Same reference numerals are used as in the first embodiment above, butin a 200-series. Although the solution with the ring 74 and thering-shaped groove 76 as described in the preceding paragraph may beadvantageous, it will be noted that the added movability is obtained inthe vibration direction only. If for instance the vibrations V aredirected left-right in FIG. 7 , then the parts of the support ring 74shown to the left and to the right in FIG. 7 would be free to move withthe horn plate 12 due to the groove 76. However, at differentcircumferential locations on the support ring 74 facing towards and awayfrom the reader in FIG. 7 , such left-right movement will not be allowedby the groove 76.

In order to address this problem, the bottom part 271 of the damperelement 270 according to the 2^(nd) embodiment may be designed as shownin FIGS. 11A and 11B. The support ring 74 in the 1^(st) embodiment isdivided in the circumferential direction into a number of individualsupport studs 274 with spaces 279 there between in the circumferentialdirection. Compared to the ring design 74, the individual support studs274 will be more flexible in all radial directions. This design willallow the support studs 274, which are in engagement with the rear sideof the horn plate 14, to move together with the horn plate 14 duringvibration damping, both radially and circumferentially in relation tothe axis A without substantially affecting the vibration dampingoperation. This design allows the support studs 274 to better follow themovement of the horn plate 14. In order to obtain a uniform movabilityin all directions, the support studs 274 may preferably have a circularcross section, i.e. essentially same dimensions in all directionsperpendicular to the axis A.

3^(rd) Embodiment

FIGS. 12A and 12B illustrate a third embodiment of a spring unit 340 foruse in situations where different dampening properties are required indifferent directions. Same reference numerals are used as above, but ina 300-series. Support studs 374 and spaces 376 are arranged as in the2^(nd) embodiment. In the 3^(rd) embodiment, the elastomeric damperelement 370 of the spring unit 340 has a non-circular configuration,such as an oval or elliptic configuration. As shown in FIG. 12B, thenon-circular damper element 370 is received in a correspondingnon-circular opening 321 in the horn plate 14. By this no-circulardesign, the assembly may present different tuning frequencies in thevertical and the horizontal direction in FIG. 12B.

4^(th) Embodiment

FIGS. 15A to 15C illustrate a 4^(th) embodiment of a damper unit 440.The same reference numerals are used as above, but in a 400-series. Theslider 450 of the damper unit 440 is shown in FIGS. 13A to 13D. Theelastomeric damper element 470 of the damper unit 440 is shown in FIGS.14A to 14C. Everything stated above for the previous embodimentsregarding the manufacture, optional bonding, function, material, etc.applies to this 4^(th) embodiment 440 also in all relevant parts. Thebase structure 12, the bracket 22 and the horn plate 14 have been drawnschematically in the figures showing the resulting damper assembly.

Like in the 2^(nd) embodiment, the damper element 470 of the damper unit440 according to the 4^(th) embodiment is divided into a plurality ofaxially extending ribs 477, which are circumferentially distributedabout the axis A of the damper unit 440 and which define spaces 478there between. The operation and advantages of the ribs as describedabove will apply in all relevant aspect to this 4^(th) embodiment also.However, this 4^(th) embodiment of the damper unit 440 presents someadditional features.

In the 4^(th) embodiment, and as seen in the direction of the axis A,each rib 477 has proximal rib part 477 a forming the vibration dampingpart of the rib 477, and a distal rib part 477 b not primarily takingpart in the vibration damping operation (FIGS. 14A to 14C). The proximalrib part 477 a has an outer radial surface 475 extending in parallelwith the axis A. The radially outer surfaces 475 of the ribs 477together form the outer engagement surface of the damper element 470. Inthe final assembly, the proximal rib part 477 a will be held in aslightly compressed state in the radial direction as described above.The distal rib part 477 b has a radially outward extending snap-lockprotrusion 473 for snap-locking purposes, similar to the snap-lockprotrusion 73 in the 1^(st) embodiment. The snap-lock protrusion 473presents a proximal inclined locking surface 473 a and a distal inclinedinsertion surface 473 b. Furthermore, in the illustrated 4^(th)embodiment, there may be a gap 473 c in the radial direction between thedistal rib part 477 b and the tubular element 458 of the slider 450. Inother embodiments, this radial gap 473 c may be dispensed with.

The horn spring element 490 of the damper unit 440 is arranged on theopposite side of the slider flange 456 on the lower tubular part 460 ofthe slider 450. What stated above in the 1^(st) embodiment regarding thestructure, the manufacturing, alternatives, and the operation of thehorn spring element 90 applies to the horn spring element 490 in this4^(th) embodiment in all relevant aspects. In the illustratedembodiment, the horn spring element 490 is molded in one piece with theelastomeric damper element 470 on the slider 450 as in the 1^(st)embodiment, with elastomeric locking elements 100 extending throughopenings 462 in the slider flange 456. In this embodiment, a portion 101of the elastomeric material also extends radially outside the outer rimof the slider flange 456. In alternative embodiments, the damper element470 and the horn spring element 490 may be held together in one piece bylocking elements 100 only or by the portion 101 only. For explanatorypurposes only, this unitary elastomeric body 470, 490, 100 is shownwithout the slider 450 in FIGS. 14A and 14C. In this embodiment, theremay also be a frictional bonding between the elastomeric elements 470,490 and the tubular parts of the slider 450.

In the 4^(th) embodiment, and as shown in FIGS. 14A to 14C and FIGS. 15Ato 15D, the elastomeric damper element 470 is provided with a first setof individual support studs 474 a and a second set of individual supportstuds 474 b. The support studs 474 a in the first set are locatedslightly closer in the axial direction to the distal insertion end ofthe damper unit by an amount A compared to the support studs 474 b inthe second set. As a non-limiting example, the value of A may be in theorder of one or a few millimeters. In the illustrated embodiment, thesupport studs 474 a, 474 b of the two sets are interlaced in thecircumferential direction. The support studs 474 a, 474 b are spacedfrom each other in the circumferential direction and spaced from theslider in the radial direction in order to be flexible in all directionstransverse to the axis A. In preferred embodiment as shown, the supportstuds 474 b in the second set are larger than the support studs 474 a inthe first set in that they have a larger cross-section perpendicular tothe axis A. In the following, these different studs will be referred toas the smaller support studs 474 a and the larger support studs 474 b.In the illustrated embodiment, the smaller support studs 474 a have acircular cross-section and the larger support studs 474 b have anelongate cross-section. The design and shape of the support studs 474 aand 474 b may vary from the example. The smaller support studs 474 ahave essentially the same function as the support studs 274 in the2^(nd) embodiment, i.e. they ensure that the contact or interfacebetween the supporting studs and the rear side of the horn plate 14 isflexible in the radial plane in order not to interfere with thevibration damping. The function of the larger studs 474 b will beexplained below.

FIGS. 16A to 16E illustrate a method for assembling a vibration damperassembly 6 (FIG. 16F) comprising three damper units 440 according to the4^(th) embodiment. FIG. 16A illustrates a damper unit 440 to be insertedfrom below into one of three openings in a horn plate 14. As in theprevious embodiments, the slider 450 and the elastomeric damper element470 of each damper unit 440 are inserted together and from one side onlyof the horn plate 14. In the illustrated embodiment, each opening of thehorn plate 14 is provided with a sleeve 20. The sleeve is preferablymade of a relatively rigid material, such as a rigid plastic materialmolded to the horn plate. One function of the sleeve 20 is to provide anaxially extended engagement surface for the damper element 470. Anotherfunction of the sleeve 20 is to protect the elastomeric damper element470 from damage during assembly and during operation.

As shown in FIG. 16B, the inner radial dimension of the sleeve isselected such that the distal inclined insertion surfaces 473 b of theribs 477 will guide the damper unit 440 into the opening and also assistin pressing or forcing the elastomeric damper element 470 through theopening.

FIG. 16C illustrates how the snap-lock protrusions 473 of the ribs 477will be pressed radially inwards as the damper unit 440 is moved throughthe opening of the sleeve 20. This radial movement may be possible dueto an inwardly radial bending of the distal rib parts 477 b and/or dueto a radial compression of the snap-lock protrusions 473.

FIG. 16D illustrates the final mounted position of the damper unit 440in relation to the horn plate 14. The final position is defined by aninsertion position where the smaller support studs 474 a are brought toengagement with the underside of the sleeve 20. The engagement may alsobe directly with the rear side of the horn plate 14. When the damperunit 440 has been fully inserted to its final position, the snap-lockprotrusions 473 of the ribs 477 will snap radially outwards as shown byarrows in FIG. 16D. The proximal inclined locking surface 473 b of eachrib 477 will now be in a locking engagement with the upper side of asnap-lock protrusion of the sleeve 20 to lock the damper unit 440 inplace. The damper unit 440 is now held axially in its final position bythe elastomeric damper element 470, namely by the smaller support studs474 a on the one hand, and the snap-lock protrusions 473 on the otherhand. The larger support studs 474 b are not in use at this stage.

As described above for the 1^(st) embodiment, during insertion of thedamper element 470, the radially outer engagement surfaces 475 of theproximal rib parts 477 a are brought into engagement with the innerengagement surface 21 of the corresponding sleeve 20, such that steeringwheel vibrations V may be transferred from the damper element 470 to thehorn plate 14. In order to achieve a proper vibration damping effect,the radial dimensions are preferably selected such that the damperelement 470 is somewhat radially pre-compressed between the slider 450and the inner engagement surface 21 of the sleeve 20 as a result of theinsertion.

When the damper elements 470 have been correctly positioned in the hornplate 14, a bolt 120 may be inserted into the bore 454 of each slider450 as shown in FIG. 16E. Each bolt 120 has a bolt head 126, acylindrical guide shaft 122 and a threaded end 124. The tubular part 452of the slider 450 may slide along the guide shaft 122. The bolts 120 aresecured in bolt holes of the supports 13 of the base structure 12.

During the final fastening of each bolt 120 (FIG. 16F), apre-compression of the corresponding horn spring part 494 is obtained.As a non-limiting example, a horn spring part 494 may be pre-compressedfrom 10 mm to 7 mm during assembly and then further compressed one or afew millimeters upon horn activation. In the final assembly 6, thedistal end 495 of each horn spring part 494 engages the associated hornspring support surface 26 of the bracket 22.

As illustrated in the enlarged-scale view in FIG. 16F, during the finalfastening of each bolt 120, the bolt head 126 may engage and axiallycompress the ribs 477 until the distal ends of the ribs 477 are in levelwith the distal end of the slider 450. As illustrated with arrows inFIG. 16F, this final compression will lock the snap-lock protrusions 473or the ribs 477 tighter to the sleeve 20 and thereby fix the damper unit440 even more securely in the axial direction in relation to the hornplate 14. In other embodiments, such a final compression may bedispensed with.

The operation of the larger/stiffer support studs 474 b will now bedescribed with reference to FIGS. 17A to 17C. Before the driveractivates the horn (FIG. 17A), the rear side of each sleeve 20 is incontact with the smaller support studs 474 a only, with an axial gap Abeing present between the rear side of the sleeve 20 and the largersupport studs 474 b.

FIG. 17B illustrates an initial stage of horn activation, where thedriver has just initiated the horn activation by pressing the hornactivation pad 8. The horn plate 14 has now moved axially a distance A.The small support studs 474 a have been axially compressed due to theirrelatively small cross-sectional dimension. Therefore, the compressionof the horn spring 494 has not yet started. When the small support studs474 a have been axially compressed to a degree where they have the sameaxial height as the larger support studs 474 b, the rear side of thesleeve 20 will have contact with both the smaller support studs 474 aand the larger support studs 474 b, as shown in the enlarged scale viewin FIG. 17B. The distance A is now eliminated. Accordingly, selectingsmall dimensions for the first set of support studs 474 a has theadvantage of both ensuring a flexible interface and ensuring an axialcompression upon horn activation.

FIG. 17C illustrates the subsequent stage of horn activation. When thedistance A towards the larger support studs 474 b has been eliminated,the total axial stiffness of all the support studs 474 a and 474 b incombination will now be sufficient for the horn spring part 494 to becompressed when the driver presses the horn activation pad 8. Forillustration purposes only, FIG. 17C shows the movement of the hornplate 14 and the compression of the horn spring in a very exaggeratedscale. In reality, this movement may be in the order of one or fewmillimeters only.

A specific advantage obtained by this design including support studs 474a and 474 b having different distance to the horn plate (in this designobtained by having different heights), and optionally with differentaxial stiffness, is that two advantageous properties may be obtained atthe same time, one relating to the vibration damping and one relating tohorn activation. With regard to vibration damping, a radially flexibleinterface is preferred between the elastomeric material and the rearside of the sleeve 20 or horn plate 14. With regard to horn activation,an axially stiff interface is preferred at the same location in order toinitiate the horn spring compression as soon as possible when the driverpresses the pad 8. This “dilemma” is solved by providing the differentsupport studs 474 a and 474 b, creating a “dynamic” support interface.

On the one hand, when no horn activation is present, the rear side ofthe horn plate 14 is supported by the relatively flexible smallersupport studs 474 a only. This has the advantage that the interfacebetween the elastomeric material and the rear side of the horn plate 14does not interfere with the vibration damping function. The largersupport studs 474 b are inactive when no horn activation is present. Onthe other hand, when horn activation is initiated, it is preferred thata fully developed horn spring force is obtained as soon as possible.Thanks to the presence of the larger and relatively stiff support studs474 b, and the relatively low axial stiffness of the smaller supportstuds 474 a, the distance A can be very quickly eliminated when hornactivation is initiated by axially compression of the smaller supportstuds 474 a, such that the desired axially stiff interface can beestablished despite that the interface is flexible during normalvibration damping.

5^(th) Embodiment

FIGS. 19A to 19C illustrate a 5^(th) embodiment of a damper unit 540.The same reference numerals are used as above, but in a 500 series. Theslider of the damper unit 540 has the same design as the slider 450 inthe 4^(th) embodiment shown in FIGS. 13A to 13D. The damper element 570of the damper unit 540 is shown in FIGS. 18A to 18C. Everything statedfor the previous embodiments regarding the manufacture, optionalbonding, function, assembly, material, ribs, support studs,alternatives, etc. applies to this 5^(th) embodiment 540 also in allrelevant parts.

The 5^(th) embodiment or the damper unit 540 differs from the 4^(th)embodiment of the damper unit 440 in that the damper unit 550 in the5^(th) embodiment does not have an integrally formed horn spring elementmade from a molded elastomeric material. Instead, separate horn springs594 are used. The horn springs 594 may be spiral springs as shown andmay typically be made from metal. In the illustrated embodiment, theslider 550 is provided with a ring-shaped groove 556 a in its lower orrear end for receiving a distal end of a horn spring 590, as shown inFIG. 20B.

FIGS. 20A to 20E illustrate a first embodiment of a method forassembling a vibration damper assembly 6 (FIG. 20F) comprising threedamper units 540 according to the 5^(th) embodiment. FIG. 20Aillustrates a damper unit 540 to be inserted from below into one ofthree mounting openings in a horn plate 14. As in the previousembodiments, the slider 550 and the elastomeric damper element 570 ofeach damper unit 540 are inserted together and from one side only of thehorn plate 14. In the illustrated embodiment, each mounting opening ofthe horn plate 14 is provided with a sleeve 20. The sleeve 20 ispreferably made of a relatively rigid material, such as a rigid plasticmaterial molded to the horn plate. One function of the sleeve 20 is toprovide an axially extended engagement surface for the damper element570. Another function of the sleeve 20 is to protect the elastomericdamper element 570 from damage during assembly and during operation. Inthis embodiment, each separate horn spring 594 has been connected to itsassociated damper unit 540 before the damper unit 540 is inserted intothe horn plate 14. In some embodiments, the radial dimensions of thehorn spring 594 and the ring-shaped groove 556 a may be selected suchthat the end of the horn spring 594 may be maintained fixed in thegroove 556 a during assembly. The advantages relating to 1-sidedmounting as described above applies to this embodiment also.

FIG. 21A illustrates a second embodiment of a method for assembling avibration damper assembly 6 comprising three damper units 540 accordingto the 5^(th) embodiment. In this embodiment, each damper unit 540 ismounted to the horn plate 14 as described above, but without theseparate horn springs 594 attached to the damper units 540. The hornsprings 594 are placed separately from the damper units 540 on thebracket surfaces 26 of bracket 22. Thereafter, as shown in FIG. 21 , thehorn plate 14 with the mounted damper units 540 is placed upon the hornsprings 594. Finally, the bolts 120 are inserted and tightened asdescribed above for the other embodiments.

Alternatives

The embodiments described above and as shown in the figures may bevaried in many ways.

In the illustrated embodiments, the horn activation mechanism ismechanical. Horn activation is accomplished by moving the horn plate 14towards the bracket 22 by sliding the sliders along the bolt shafts.During horn activation, the horn spring is compressed. When the driverreleases the horn activation pad 8, the horn spring (elastomeric ormetal) will return the horn plate 14 to its default position. In otherembodiments, the horn activation mechanism may be electronic. In suchembodiments, the horn plate 14 does not have to be moved towards thebase structure 12. Instead, the horn is activated by other means,including electronic contacts. However, there is still a need forvibration damping, and the horn plate may be connected to the basestructure 12 via damper units as described, but without use of any hornsprings. In such embodiments, the slider will actually not act as aslider designed to slide on the bolt shaft during horn activation.Instead, the slider part would rather be a mounting sleeve in which thebolts are inserted to mount the damper unit. Since no sliding movementis present, there is no need for any horn springs. In such embodiments,the radial slider flange may also be dispensed with.

In the illustrated embodiments, the guide shaft is part of a boltscrewed into the vibrating base structure. The guide shaft may beimplemented differently, for instance by a guide shaft made in one piecewith the vibrating structure and optionally with a free threaded end forsecuring the assembly by a nut. Also, it may in some embodiments bepossible to have the bolt oriented the opposite direction, i.e. to bescrewed into the horn plate instead.

In alternative embodiments, the sleeves 20 of the horn plate aredispensed with and the damper elements are connected to the horn plate14 in a different way, optionally in direct contact with the horn plate14.

The second tubular portion of the slider may in other embodiments extendfurther into the horn spring part, but preferably not all the way inorder to allow movement of the slider upon horn activation. In someembodiment, the second tubular portion is dispensed with and the hornspring element is attached to the slider in some other way, such as tothe flange only.

In some embodiments, the outer engagement surface of the damper elementmay extend substantially 360 degrees circumferentially around the axisof the damper unit, such that vibrations may be transferred inessentially all radial directions. Such embodiments are considered toinclude ribbed designs also, where the outer engagement surface is notcontinuous in the circumferential direction.

In other embodiments, the outer engagement surface of the damper elementmay be present in some directions only if the damper unit is configuredto transfer vibrations in some specific directions only. This may beimplemented in various ways, such as by arranging inner protruding partsin the mounting opening of the horn plate defining circumferentiallylimited inner engagement surfaces, such as inner protruding parts on thesleeves. This may also be implemented by designing the elastomericdamper element with engagement surfaces in some directions only. In suchembodiments where one single damper unit is arranged to transfervibrations in specific directions only, the complete assembly maycomprise a number of damper units arranged to handle vibrations indifferent directions. As an example, One or more damper units may beconfigured to dampen vibrations in a vertical direction and one or moreother damper units may be configured to dampen vibrations in ahorizontal direction.

In alternative embodiments, the slider and the corresponding channels orbores of the elastomeric elements may have a non-circular cross-section,for instance if different damping properties in different directions aredesired and the damper unit therefore has to be oriented in a specificway on the guide shaft.

Further Inventive Concept

According to a further inventive concept, there is provided a damperunit as described in any of the preceding embodiments, but without anysleeve or slider. FIGS. 24A to 24C illustrate such an alternative. Thefigures are identical to FIGS. 18A to 18C except that the slider and thebottom part of the elastomeric element has been removed. Such a damperunit may be made manufactured and also assembled as a single, one-pieceelastomeric damper element comprising one or more of the structures andfunctions as described above. The elastomeric damper element may thushave an integrally formed horn spring, or no horn spring at all. Thelocking procedure, optionally using the bolt head as described above forcompression, may also be used. In mounting the damper unit, a bolt maybe introduced through a central channel or hole in of the elastomericdamper unit and optionally be in direct contact with a radially innersurface of the elastomeric damper unit.

According to this further inventive concept, there may be provided adamper unit for use in a frequency-tuned vibration damper assembly for asteering wheel, said damper unit having an insertion end and an oppositerear end, and being configured to be inserted with its insertion endthrough a mounting opening provided in a horn plate of said damperassembly,

said damper unit comprising an elastomeric damper element which moldedon a radial outer side of the sleeve such that the sleeve and the damperelement together form a unitary structure,

wherein:

the elastomeric damper element presents an elastomeric insertion partconfigured to be inserted into the mounting opening of the horn plate,and an elastomeric support part configured to define a final mountingposition of the damper unit;

the elastomeric insertion part presents a plurality of elastomeric ribswhich extend at least partially along said axis and are mutually spacedin a circumferential direction in relation to said axis, said ribstogether forming a radially outer engagement surface configured to bebrought into direct engagement with an inner surface of said mountingopening;

the radially outer engagement surface has a first radial dimension, andthe elastomeric support part has a second radial dimension, larger thansaid first radial dimension;

at least some of the elastomeric ribs present a radially outwardextending snap-lock protrusion configured to be inserted through themounting opening to snap-lock the damper unit in its final mountingposition; and

said elastomeric support part presents a plurality of elastomericsupport studs, which are mutually spaced in the circumferentialdirection and extend at least partially in the direction of said axis,said elastomeric support studs being flexible in all directionstransverse to said axis.

According to this further inventive concept, there may also be provideda method for use in making a frequency-tuned vibration damper assemblyfor dampening vibrations in a steering wheel, said method comprising:

using one or more damper units, each damper unit comprising anelastomeric vibration damper element having:

-   -   an elastomeric insertion part presenting one or more radially        outward extending snap-lock protrusions at an insertion end, and        a radially outer engagement surface axially spaced from the        snap-lock protrusions, said radially outer engagement surface        having a first radial dimension, and    -   an elastomeric support part which has a second radial dimension,        larger than said first radial dimension;

and

inserting each damper unit, in an insertion direction, into anassociated mounting opening in a horn plate along an axis of the damperunit,

wherein the damper unit is inserted into the mounting opening until afinal insertion position is reached in which:

-   -   the radially outer engagement surface of the elastomeric        insertion portion is in direct contact with an inner surface of        the mounting opening,    -   the snap-lock protrusions have been inserted through the        mounting opening to form a snap-lock of the damper unit in        relation to the horn plate, and    -   the elastomeric support part has been brought into axial contact        with a rear side of the horn plate

Structures, designs, methods and alternatives as described above for the1^(st) to the 4^(th) embodiments may be used in this further inventiveconcept in all relevant parts.

1. A method making a frequency-tuned vibration damper assembly fordampening vibrations in a steering wheel, said method comprisinginserting a damper unit in an insertion direction into a mountingopening of a horn plate along an axis of the damper unit, said damperunit comprising an elastomeric damper element, which is molded on aradial outer side of a sleeve such that the sleeve and the damperelement together form a unitary structure, wherein the damper unit isinserted into the mounting opening in the insertion direction until afinal insertion position of the damper unit is reached in whichinsertion position: a plurality of radially outward extending snap-lockprotrusions of the elastomeric damper element, formed at an insertionend of the damper unit, have been inserted in the insertion directionthrough the mounting opening to form a snap-lock of the damper unit inrelation to the horn plate on a front side of the horn plate, a radiallyouter elastomeric engagement surface of the elastomeric damper element,axially spaced from the snap-lock protrusions, has been inserted intothe mounting opening and brought into radial engagement with a radiallyinner surface of the mounting opening of the horn plate, and anelastomeric support part of the elastomeric damper element has beenbrought into axial contact with a rear side of the horn plate fordefining the final insertion position.
 2. The method as claimed in claim1, wherein the radially outer engagement surface has a first radialdimension, and wherein the elastomeric support part of the elastomericelement has a second radial dimension that is larger than the firstradial dimension.
 3. The method as claimed in claim 1, furthercomprising: inserting a guide shaft, in a direction opposite to theinsertion direction, through a bore of the sleeve; and connecting adistal end of the guide shaft to a base structure, which is fixed to thesteering wheel and which is subjected to vibrations to be dampened,wherein the sleeve of the damper unit forms a slider being configured toslide along the guide shaft.
 4. The method as claimed in claim 3,wherein the guide shaft is a bolt shaft of a bolt, and wherein a bolthead of the bolt is configured to act as a stop for limiting axialsliding movement of the slider along the bolt shaft.
 5. The method asclaimed in claim 4, further comprising connecting the bolt such that atleast part of the elastomeric damper element is compressed by the bolthead.
 6. The method as claimed in claim 1, further comprising connectinga mass to a base structure, which is fixed to the steering wheel andwhich is subjected to vibrations to be dampened, for allowing movementof the mass transverse to said axis, wherein the elastomeric damperelement and the mass are configured to operate together as a frequencytuned spring-mass system forming a frequency tuned dynamic damper fordampening said frequencies.
 7. The method as claimed in claim 6, whereinconnecting the mass to the base structure via the elastomeric damperelement comprises mounting an airbag assembly on the horn plate, andwherein a weight of the mass comprises at least a weight of the hornplate and a weight of the airbag assembly.
 8. The method as claimed inclaim 1, wherein the elastomeric damper element is molded on the radialouter side of the sleeve such that parts of the elastomeric damperelement extend through locking openings of a flange extending radiallyoutwards from the sleeve.
 9. The method as claimed in claim 1, whereinthe elastomeric vibration damper element is molded on a first part ofthe sleeve, and an elastomeric attachment part of an elastomeric hornspring element is molded on a second part of the sleeve, saidelastomeric horn spring element being configured to exert a force on thesleeve in the direction of the axis before and upon a horn activation onthe steering wheel.
 10. The method as claimed in claim 11, wherein thesleeve comprises: a tubular element extending along said axis anddefining said bore; and a flange extending radially outwards from thetubular element, and wherein the elastomeric damper element and theelastomeric horn spring element are located on opposite axial sides ofthe flange.
 11. The method as claimed in claim 1, wherein an elastomericinsertion part of the elastomeric damper element includes a plurality ofelastomeric ribs, which extend at least partially along said axis andare mutually spaced in a circumferential direction in relation to saidaxis, said ribs together forming the radially outer engagement surfaceconfigured to be brought into engagement with the radially inner surfaceof the mounting opening.